The Resonant Piezoelectric Actuator Research For The CMG Framework

With the rapid development of the aerospace, the requirements to the spacecraft attitude adjustment in the space environment are also improving. Spacecraft attitude control systems generally use the Control Moment Gyro(CMG for short) as the main implementing agency. At this stage because of the sustained high growth of spacecraft type and quantity, the reliability, accuracy, stability and other requirements of the aerospace implementing agency are also improving. Now a lot of domestic and foreign CMG in the spacecrafts use traditional electromagnetic motor to achieve driving action, This drive mode has a lot of disadvantages such as complicated structure, high weight and low accuracy; In addition, under the influence of extremely low temperatures or cosmic rays, parts of this drive mechanism will often lose efficacy. Therefore, at this stage it is high time to develop new drive mode to overcome the above technical bottlenecks problem.Currently, the piezoelectric actuator is a new drive mechanism which has low speed high torque output, no electromagnetic interference, high power density, fast response, good low temperature performance, automatically locked after power off, no lubrication, flexible configuration and many other advantages, so it can be applied in the CMG drive system. For the above reasons, this paper researches on a kind of framework of CMG based on the resonant piezoelectric actuator. Compared with some of the existed framework structure of CMG, this structure is more compacted, which reduces the size and weight of the overall framework. This structure also has the outstanding advantages of the piezoelectric actuator mechanism.Firstly, the preliminary framework structure of CMG was designed and briefly analyzed, and this paper pointed out the core part of the framework was the resonant piezoelectric actuator which had an opposite driving direction on the two ends. According to this driving feature, the paper designed its basic configuration, and completed the actuation principle analysis, which proved its feasibility; for this new configuration, the structural parameters were optimized and the final size was determined through the modal analysis and the sensitivity analysis. The trajectory and displacement parameters of the particle on the driving surface were researched through the transient analysis. The impedance matching design was completed based on the impedance analysis. Based on the results of the theory and simulation, the final piezoelectric actuators physical prototype was developed, and a test device was designed to complete the prototype performance testing. Based on the completed piezoelectric actuators physical prototype, the framework mechanism of the CMG was designed and processed. The diameter of CMG was 120 mm. Some experiments on this mechanism were completed. When the two-phase AC excitation signals were applied to the piezoelectric actuator, the speed of the CMG was about 102r/min. The signals’ voltage was 100 V, its’ frequency was 23.8k Hz and its’ phase difference was 90°. When the output speed is 3.6r/min, the output torque is 2.964N·m.